Dimensões de fibras em árvore de Eucalyptus sp. com madeira de reação

Abstract

Trees that, by genotype or mechanical stimuli, develop wood of reaction have in their wood differentiated fibers. The dimensions of wood fibers are directly related to their physical and mechanical characteristics, and can be determinant for their final use. This work had as objective to determine the variation of the fiber dimensions in different heights and different radial positions in the trunk of Eucalyptus sp. For this, 8 discs were removed every 1.5 meters from the selected tree, from which samples were drawn in the radial direction of the four sides of the marrow, respecting the following directions: reaction wood, wood post, right side to the medulla, left side To the marrow. In each of these positions samples were spaced apart every 2.5 cm. The maceration was done and the fibers were observed under a microscope, measuring its length, width, lumen diameter and wall thickness. For the wood of the studied tree, it was possible to conclude that: i) The average overall length of the fibers was 1.12 mm, the mean general wall thickness was 6.69 μm, the mean overall diameter was 18.01 μm and the mean overall diameter of the lumen was 4.65 μm. Ii) The reaction wood presented fibers with greater lengths, smaller wall thicknesses, fiber width and lumen diameter when compared to the opposite wood. Iii) The characteristics of the reaction wood were more evident in the intermediate heights of the tree (4,5; 6,0 and 7,5).